here's nbc's ron mott. >> reporter: police say the christmas eve ambush of four firefighters battling a massive house fire in new york was spelled out by the suspected arsonist and shooter in chilling, typewritten detail. >> quote, i still have to get ready to see how much of the neighborhood i can burn down and do i like doing best, killing people. >> reporter: authority ts say 62 years william spengler, who served prison time for killing his grandmother more than 30 years ago, shot at first responders who arrived at his burning house, the fire spreading to six other homes. >> we are being shot at. multiple firemen down. i am shot. i think he's using an assault rifle. >> he was equipped to go to war to kill innocent people. >> reporter: the gunman was well-fortified with weapons and ammo. the same model used in the newtown, connecticut, school shooting. tomasz kaczowka and mike chiapperini were killed. spengler killed himself. and late today, human remains were found in spengler's house and suspect they belong to his missing sister. >> microsoft is always the burning question. i'm no